Molecular and Electronic Structures and Single-Molecule Magnet Behavior of Tris(thioether)-Iron Complexes Containing Redox-Active α-Diimine Ligands

Incorporating radical ligands into metal complexes is one of the emerging trends in the design of single-molecule magnets (SMMs). While significant effort has been expended to generate multinuclear transition metal-based SMMs with bridging radical ligands, less attention has been paid to mononuclear transition metal–radical SMMs. Herein, we describe the first α-diiminato radical-containing mononuclear transition metal SMM, namely, [κ2-PhTt tBu]­Fe­(AdNCHCHNAd) (1), and its analogue [κ2-PhTt tBu]­Fe­(CyNCHCHNCy) (2) (PhTt tBu = phenyltris­(tert-butylthiomethyl)­borate, Ad = adamantyl, and Cy = cyclohexyl). 1 and 2 feature nearly identical geometric and electronic structures, as shown by X-ray crystallography and electronic absorption spectroscopy. A more detailed description of the electronic structure of 1 was obtained through EPR and Mössbauer spectroscopies, SQUID magnetometry, and DFT, TD-DFT, and CAS calculations. 1 and 2 are best described as high-spin iron­(II) complexes with antiferromagnetically coupled α-diiminato radical ligands. A strong magnetic exchange coupling between the iron­(II) ion and the ligand radical was confirmed in 1, with an estimated coupling constant J \u3c −250 cm–1 (J = −657 cm–1, DFT). Calibrated CAS calculations revealed that the ground-state Fe­(II)−α-diiminato radical configuration has significant ionic contributions, which are weighted specifically toward the Fe­(I)-neutral α-diimine species. Experimental data and theoretical calculations also suggest that 1 possesses an easy-axis anisotropy, with an axial zero-field splitting parameter D in the range from −4 to–1 cm–1. Finally, dynamic magnetic studies show that 1 exhibits slow magnetic relaxation behavior with an energy barrier close to the theoretical maximum, 2|D|. These results demonstrate that incorporating strongly coupled α-diiminato radicals into mononuclear transition metal complexes can be an effective strategy to prepare SMMs

Combined sedation with midazolam/propofol for gastrointestinal endoscopy in elderly patients

<p>Abstract</p> <p>Background</p> <p>Although gastrointestinal endoscopy with sedation is increasingly performed in elderly patients, data on combined sedation with midazolam/propofol are very limited for this age group.</p> <p>Methods</p> <p>We retrospectively analyzed 454 endoscopic procedures in 347 hospitalized patients ≥ 70 years who had received combined sedation with midazolam/propofol. 513 endoscopic procedures in 397 hospitalized patients < 70 years during the observation period served as controls. Characteristics of endoscopic procedures, co-morbidity, complications and mortality were compared.</p> <p>Results</p> <p>Elderly patients had a higher level of co-morbidity and needed lower mean propofol doses for sedation. We observed no major complication and no difference in the number of minor complications. The procedure-associated mortality was 0%; the 28-day mortality was significantly higher in the elderly (2.9% vs. 1.0%).</p> <p>Conclusions</p> <p>In this study on elderly patients with high level co-morbidity, a favourable safety profile was observed for a combined sedation with midazolam/propofol with a higher sensitivity to propofol in the elderly.</p

Methylphenidate and Attributions in Boys With Attention-Deficit Hyperactivity Disorder

In Experiment 1, 28 attention-deficit hyperactivity disorder (ADHD) boys underwent a double-blind, placebo-controlled medication assessment in a summer day-treatment program. Daily, boys were asked questions to assess their attributions for and evaluations of their behavior. Objective measures showed improved behavior with methylphenidate; however, boys tended to attribute their performance to effort rather than to medication, particularly when medicated. Experiment 2 involved 38 ADHD boys the following summer and replicated the procedures in Experiment 1, with the addition of a no-pill condition and a comparison of attributions for success and failure outcomes. Simply taking a pill (no-pill vs. placebo comparison) did not show significant effects, whereas the results of Experiment 1 were replicated with placebo–methylphenidate comparisons. Across drug conditions a self-enhancing attributional pattern was obtained; the majority of attributions for success were to ability or effort, whereas attributions for failure were to the pill or to counselors

Methylphenidate and Attributions in Boys With Attention-Deficit Hyperactivity Disorder

In Experiment 1, 28 attention-deficit hyperactivity disorder (ADHD) boys underwent a double-blind, placebo-controlled medication assessment in a summer day-treatment program. Daily, boys were asked questions to assess their attributions for and evaluations of their behavior. Objective measures showed improved behavior with methylphenidate; however, boys tended to attribute their performance to effort rather than to medication, particularly when medicated. Experiment 2 involved 38 ADHD boys the following summer and replicated the procedures in Experiment 1, with the addition of a no-pill condition and a comparison of attributions for success and failure outcomes. Simply taking a pill (no-pill vs. placebo comparison) did not show significant effects, whereas the results of Experiment 1 were replicated with placebo–methylphenidate comparisons. Across drug conditions a self-enhancing attributional pattern was obtained; the majority of attributions for success were to ability or effort, whereas attributions for failure were to the pill or to counselors